Apparatus and method for transmitting and receiving information through fast feedback channel in broadband wireless communication system

ABSTRACT

An apparatus and method for transmitting information through a fast feedback channel in a wireless communications system are provided. The apparatus includes a plurality of mappers for mapping a sequence, corresponding to an index to be fed back, to a first set of resource blocks in a fast feedback channel by using a first mapping pattern and to a second set of resource blocks in the fast feedback channel by using a second mapping pattern, and a transmitter for transmitting the sequence mapped to a plurality of sets of resource blocks, wherein the sequence is mapped to each of the plurality of sets of resource blocks, and wherein each element of the sequence is mapped to each resource block.

PRIORITY

This application is a continuation of prior application Ser. No.12/540,655, filed on Aug. 13, 2009, which claims the benefit under 35U.S.C. §119(a) of a Korean patent application filed in the KoreanIntellectual Property Office on Aug. 13, 2008 and assigned Serial No.10-2008-0079418, a Korean patent application filed in the KoreanIntellectual Property Office on Feb. 25, 2009 and assigned Serial No.10-2009-0016051, and a Korean patent application filed in the KoreanIntellectual Property Office on Mar. 5, 2009 and assigned Serial No.10-2009-0019029, the entire disclosures of all of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a broadband wireless communicationsystem. More particularly, the present invention relates to an apparatusand method for transmitting/receiving information through a fastfeedback channel having limited capacity in a broadband wirelesscommunication system.

2. Description of the Related Art

Physical channels for transmitting UpLink (UL) fast feedback informationare present in Orthogonal Frequency Division Multiple Access(OFDMA)-based communication systems. Examples of the UL fast feedbackinformation may include a variety of information, such as, aSignal-to-Noise Ratio (SNR) or a Carrier-to-Interference Ratio (CIR), aModulation and Coding Scheme (MCS) preferred by a Mobile Station (MS),information for selecting a Flexible Frequency Reuse (FFR), a beamforming index, and the like.

The UL fast feedback information is small but is significantly importantfor operating a communication system. Thus, high reliability has to beensured when the UL fast feedback information is transmitted. However,to avoid a waste of resources, a physical channel for transmitting highspeed feedback information is not allocated generally with a largeamount of frequency-time resources. Therefore, an effectivemodulation/demodulation scheme is required for reliable transmissionusing limited resources.

The OFDMA-based communication systems generally use non-coherentmodulation/demodulation to transmit and receive the UL fast feedbackinformation. Signal streams orthogonal to each other are used for thenon-coherent modulation/demodulation. Thus, there is a restriction onthe number of bits of information that can be transmitted using limitedfrequency-time resources. In addition, since the same signal istransmitted using different frequency resources to obtain a frequencydiversity gain, a resource loss is greater than an information bit loss.

As described above, the fast feedback information is necessary forsystem operation and thus demands high reliability. However, resourceutility efficiency may decrease by the orthogonal signal streams forensuring high reliability and by the use of a diversity scheme.

Therefore, a need exists for an apparatus and method for effectivelyusing resources in a broadband wireless communication system whilemaintaining high reliability.

SUMMARY OF THE INVENTION

An aspect of the present invention is to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentinvention is to provide an apparatus and method for effectively using afast feedback channel having a limited capacity in a broadband wirelesscommunication system.

Another aspect of the present invention is to provide an apparatus andmethod for transmitting and receiving quasi-orthogonal signal streamsthrough a fast feedback channel in a broadband wireless communicationsystem.

Still another aspect of the present invention is to provide an apparatusand method for utilizing a quasi-orthogonal signal stream group havingcorrelation values less than or equal to a threshold in a broadbandwireless communication system.

Yet another aspect of the present invention is to provide an apparatusand method for utilizing a quasi-orthogonal signal stream groupconsisting of an orthogonal sub-signal stream in a broadband wirelesscommunication system.

A further aspect of the present invention is to provide an apparatus andmethod for utilizing a quasi-orthogonal signal stream group generatedusing orthogonal sub-signal streams and a phase difference vector in abroadband wireless communication system.

In accordance with an aspect of the present invention, atransmitting-end apparatus in a wireless communication system isprovided. The apparatus includes a plurality of mappers for mapping asequence, corresponding to an index to be fed back, to a first set ofresource blocks in a fast feedback channel by using a first mappingpattern and to a second set of resource blocks in the fast feedbackchannel by using a second mapping pattern, and a transmitter fortransmitting the sequence mapped to a plurality of sets of resourceblocks, wherein the sequence is mapped to each of the plurality of setsof resource blocks, and wherein each element of the sequence is mappedto each resource block, wherein a mapping order of elements of thesequence in the first mapping pattern is different from a mapping orderof elements of the sequence in the second mapping pattern, wherein thefirst set of resource blocks and second set of resource blocks have apredetermined same number of resource blocks each other, and wherein thefirst set of resource blocks is differently located from the second setof resource block in the fast feedback channel.

In accordance with another aspect of the present invention, a method fortransmitting feedback information through a fast feedback channel in awireless communication system is provided. The method includes mapping asequence, corresponding to an index to be fed back, to a first set ofresource blocks in a fast feedback channel by using a first mappingpattern and to a second set of resource blocks in the fast feedbackchannel by using a second mapping pattern, and transmitting the sequencemapped to a plurality of sets of resource blocks, wherein the sequenceis mapped to each of the plurality of sets of resource blocks, andwherein each element of the sequence is mapped to each resource block,wherein a mapping order of elements of the sequence in the first mappingpattern is different from a mapping order of elements of the sequence inthe second mapping pattern, wherein the first set of resource blocks andsecond set of resource blocks have a predetermined same number ofresource blocks each other, and wherein the first set of resource blocksis differently located from the second set of resource block in the fastfeedback channel.

Other aspects, advantages and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates an example of a structure of a high feedback channelin a broadband wireless communication system according to an exemplaryembodiment of the present invention;

FIGS. 2A and 2B illustrate examples of a method for mapping aquasi-orthogonal signal stream in a broadband wireless communicationsystem according to an exemplary embodiment of the present invention;

FIG. 3 is a block diagram illustrating a structure of a transmitting endin a broadband wireless communication system according to an exemplaryembodiment of the present invention;

FIG. 4 is a block diagram illustrating a structure of a receiving end ina broadband wireless communication system according to an exemplaryembodiment of the present invention;

FIGS. 5A to 5C are block diagrams illustrating a structure of areceiving end in a broadband wireless communication system according toan exemplary embodiment of the present invention;

FIG. 6 is a flowchart illustrating a process of transmitting aquasi-orthogonal signal stream of a transmitting end in a broadbandwireless communication system according to an exemplary embodiment ofthe present invention;

FIG. 7 is a flowchart illustrating a process of detecting aquasi-orthogonal signal stream of a receiving end in a broadbandwireless communication system according to an exemplary embodiment ofthe present invention; and

FIGS. 8A to 8C are flowcharts illustrating a process of detecting aquasi-orthogonal signal stream of a receiving end in a broadbandwireless communication system according to an exemplary embodiment ofthe present invention.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features andstructures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. Also, descriptions of well-known functions and constructionsare omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention are provided for illustration purpose only and not forthe purpose of limiting the invention as defined by the appended claimsand their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

By the term “substantially” it is meant that the recited characteristic,parameter, or value need not be achieved exactly, but that deviations orvariations, including for example, tolerances, measurement error,measurement accuracy limitations and other factors known to skill in theart, may occur in amounts that do not preclude the effect thecharacteristic was intended to provide.

Exemplary embodiments of the present invention provide a technique foreffectively using a fast feedback channel with a limited capacity in abroadband wireless communication system.

Although an Orthogonal Frequency Division Multiplexing (OFDM)/OrthogonalFrequency Division Multiple Access (OFDMA)-based wireless communicationsystem is described hereinafter for example, exemplary embodiments ofthe present invention may also apply to other types of wirelesscommunication systems.

FIG. 1 illustrates an example of a structure of a high feedback channelin a broadband wireless communication system according to an exemplaryembodiment of the present invention.

Referring to FIG. 1, the fast feedback channel consists of threesub-carrier bundles 111, 113 and 115, and each sub-carrier bundle rangestwo sub-carriers and 6 OFDM symbols. That is, one sub-carrier bundleincludes 12 modulation symbols. However, the present invention is notlimited thereto and may also apply to wireless communication systemsusing other types of fast feedback channels.

A Transmit (Tx) signal stream for feedback is designed based on a singlesub-carrier bundle. That is, when using the fast feedback channel havingthe format of FIG. 1, the Tx signal stream is designed based on 12 tonesincluded in one sub-carrier bundle. When signal streams having perfectorthogonality are intended to be transmitted using the 12 tones, up to12 orthogonal signal streams are available. For example, when M tonesare usable, the orthogonal signal streams are generated as expressed byEquation (1) below.

C _(i) [m]=exp[j2πi/M],0≦i,m≦M−1  (1)

In Equation (1), C_(i)[m] denotes an (m+1)^(th) element of an (i+1)^(th)orthogonal signal stream, and M denotes a length of an orthogonal signalstream.

The orthogonal signal streams generated by Equation (1) above generallyhave an M-ary Phase Shift Keying (PSK) modulation format. When thelength M of the orthogonal stream has a specific pattern such as amultiple of 4, the generated orthogonal signal stream may have aQuadrature Phase Shift Keying (QPSK) or Binary Phase Shift Keying (BPSK)modulation format.

When using the orthogonal signal stream having a length of M, a numberof bits of feedback information is limited to log₂ M. Therefore, in acase where the number of bits of the feedback information needs to beincreased, perfect orthogonality is abandoned between signal streams.Accordingly, an exemplary embodiment of the present invention proposes asignal stream group designed such that a correlation value between allpossible signal stream pairs is less than or equal to a threshold whileabandoning perfect orthogonality. That is, in order to maximizeasynchronous detection performance of a receiving end, an exemplaryembodiment of the present invention maintains a correlation valuebetween any different signal streams belonging to a quasi-orthogonalsignal stream group to a minimum level. The correlation value betweenthe signal streams may be expressed by Equation (2) below.

$\begin{matrix}{\rho_{ik} = {{\sum\limits_{m = 0}^{M - 1}{{C_{i}\lbrack m\rbrack}{C_{k}^{*}\lbrack m\rbrack}}}}} & (2)\end{matrix}$

In Equation (2), ρ_(ik) denotes a correlation value between an i^(th)signal stream and a k^(th) signal stream, C_(i)[m] denotes an (m+1)^(th)element of an i^(th) signal stream, and M denotes a length of a signalstream.

The quasi-orthogonal signal stream group is designed differentlyaccording to the number of bits of feedback information, i.e., thenumber of codewords of the feedback information. Accordingly, anexemplary embodiment of the present invention describes an example of aquasi-orthogonal signal stream group capable of indicating 64 codewordsby using a signal stream having a length of 12.

The quasi-orthogonal signal stream group capable of indicating the 64codewords is generated as follows.

In the quasi-orthogonal signal stream group capable of indicating the 64codewords, a correlation value between different signal streams ismaintained to be less than or equal to 4. The signal stream having alength of 12 consists of three sub-signal streams having a length of 4.In this case, each sub-signal stream is one of the orthogonal signalstreams having a length of 4. The orthogonal signal streams having alength of 4 may be generated using a 4-point Discrete Fourier Transform(DFT) as illustrated in Equation (1) above, or may be generated using aHadamard code as illustrated in Equation (3) below.

v ₀=[1,1,1,1]

v ₁=[1,−1,1,−1]

v ₂=[1,1,−1,−1]

v ₃=[1,−1,−1,1]  (3)

In Equation (3), v_(k) denotes a (k+1)th orthogonal sub-signal stream.

If two different quasi-orthogonal signal streams have only one identicalorthogonal sub-signal stream, a correlation value between thequasi-orthogonal signal streams does not exceed 4, i.e., a length of asub-signal stream. An orthogonal sub-signal stream group having theabove characteristic may be generated by using a Reed-Solomon (RS) codewhose alphabet is each orthogonal sub-signal stream and which has aminimum Hamming distance of 2 and a Galois Field (GF) of 4. That is, 16quasi-orthogonal signal streams as illustrated in Equation (4) below aregenerated from the orthogonal signal streams as illustrated in Equation(3) above.

$\begin{matrix}\begin{bmatrix}\left( {v_{0},v_{0},v_{0}} \right) & \left( {v_{0},v_{1},v_{2}} \right) & \left( {v_{0},v_{2},v_{3}} \right) & \left( {v_{0},v_{3},v_{1}} \right) \\\left( {v_{1},v_{2},v_{0}} \right) & \left( {v_{2},v_{3},v_{1}} \right) & \left( {v_{3},v_{1},v_{0}} \right) & \left( {v_{2},v_{0},v_{1}} \right) \\\left( {v_{3},v_{0},v_{2}} \right) & \left( {v_{1},v_{0},v_{3}} \right) & \left( {v_{1},v_{3},v_{2}} \right) & \left( {v_{2},v_{1},v_{3}} \right) \\\left( {v_{3},v_{2},v_{1}} \right) & \left( {v_{1},v_{1},v_{1}} \right) & \left( {v_{2},v_{2},v_{2}} \right) & \left( {v_{3},v_{3},v_{3}} \right)\end{bmatrix} & (4)\end{matrix}$

In Equation (4), v_(k) denotes a (k+1)th orthogonal sub-signal stream.

Each orthogonal sub-signal stream constituting the quasi-orthogonalsignal streams as illustrated in Equation (4) corresponds to the samefrequency-time resource bundle. Therefore, unlike in the RS code thatmaintains only the minimum Hamming distance, an additional phasedifference is applied to a sub-signal stream to increase the number ofquasi-orthogonal signal streams while maintaining a correlation valuebetween the quasi-orthogonal signal streams. For example, a phasedifference vector for providing an additional phase difference isexpressed by Equation (5) below.

u ₀=(1,1,1)

u ₁=(1,1,−1)

u ₂=(1,−1,1)

u ₃=(1,−1,−1)  (5)

In Equation (5), u_(k) denotes a (k+1)th phase difference vector.

Phase difference vectors as illustrated in Equation (5) above arerespectively applied to quasi-orthogonal signal streams as illustratedin Equation (4) to obtain a quasi-orthogonal signal stream group capableof expressing 64 codewords as illustrated in Equation (6) below.

$\begin{matrix}{\left( {p_{1},p_{2},p_{3}} \right) = \begin{bmatrix}\left( {v_{l},v_{m},v_{n}} \right) \\\left( {v_{l},v_{m},{- v_{n}}} \right) \\\left( {v_{l},{- v_{m}},v_{n}} \right) \\\left( {v_{l},{- v_{m}},{- v_{n}}} \right)\end{bmatrix}} & (6)\end{matrix}$

In Equation (6), (p₁, p₂, p₃) denotes a quasi-orthogonal signal stream,v_(l) denotes an l^(th) orthogonal sub-signal stream, v_(m) denotes anm^(th) orthogonal sub-signal stream, and v_(n) denotes an n^(th)orthogonal sub-signal stream. Herein, a combination of (l,m,n) is one ofcombinations constituting the signal stream of Equation (4) above.

In the quasi-orthogonal signal stream group generated as illustrated inEquation (6) above, the product between different phase differencevectors includes at least one different sign, i.e., ‘+’ or ‘−’, and thusa correlation value between quasi-orthogonal signal streams ismaintained to be less than or equal to 4 regardless of which orthogonalsub-signal stream is selected. Table 1 below illustrates an example of amapping relation between a quasi-orthogonal signal stream group based onthe above generation scheme and a 6-bit fast feedback information bit.

TABLE 1 index of sub- signal stream phase difference signal streamcodeword (l, m, n) vector (BPSK) (BPSK) 0b000000 (0, 0, 0) (1, 1, 1)111111111111 0b000001 (0, 0, 0) (1, −1, 1) 111100001111 0b000010 (0, 0,0) (1, 1, −1) 111111110000 0b000011 (0, 0, 0) (1, −1, −1) 1111000000000b000100 (0, 1, 2) (1, 1, 1) 111111001001 0b000101 (0, 1, 2) (1, −1, 1)111100111001 0b000110 (0, 1, 2) (1, 1, −1) 111111000110 0b000111 (0, 1,2) (1, −1, −1) 111100110110 0b001000 (0, 2, 3) (1, 1, 1) 1111001110100b001001 (0, 2, 3) (1, −1, 1) 111101101010 0b001010 (0, 2, 3) (1, 1, −1)111110010101 0b001011 (0, 2, 3) (1, −1, −1) 111101100101 0b001100 (0,3, 1) (1, 1, 1) 111110101100 0b001101 (0, 3, 1) (1, −1, 1) 1111010111000b001110 (0, 3, 1) (1, 1, −1) 111110100011 0b001111 (0, 3, 1) (1, −1,−1) 111101010011 0b010000 (1, 2, 0) (1, 1, 1) 110010011111 0b010001 (1,2, 0) (1, −1, 1) 110001101111 0b010010 (1, 2, 0) (1, 1, −1) 1100100100000b010011 (1, 2, 0) (1, −1, −1) 110001100000 0b010100 (2, 3, 0) (1, 1, 1)100110101111 0b010101 (2, 3, 0) (1, −1, 1) 100101011111 0b010110 (2, 3,0) (1, 1, −1) 100110100000 0b010111 (2, 3, 0) (1, −1, −1) 1001010100000b011000 (3, 1, 0) (1, 1, 1) 101011001111 0b011001 (3, 1, 0) (1, −1, 1)101000111111 0b011010 (3, 1, 0) (1, 1, −1) 101011000000 0b011011 (3, 1,0) (1, −1, −1) 101000110000 0b011100 (2, 0, 1) (1, 1, 1) 1001111111000b011101 (2, 0, 1) (1, −1, 1) 100100001100 0b011110 (2, 0, 1) (1, 1, −1)100111110011 0b011111 (2, 0, 1) (1, −1, −1) 100100000011 0b100000 (3, 0,2) (1, 1, 1) 101011111001 0b100001 (3, 0, 2) (1, −1, 1) 1010000010010b100010 (3, 0, 2) (1, 1, −1) 101011110110 0b100011 (3, 0, 2) (1, −1,−1) 101000000110 0b100100 (1, 0, 3) (1, 1, 1) 110011111010 0b100101 (1,0, 3) (1, −1, 1) 110000001010 0b100110 (1, 0, 3) (1, 1, −1) 1100111101010b100111 (1, 0, 3) (1, −1, −1) 110000000101 0b101000 (1, 3, 2) (1, 1, 1)110010101001 0b101001 (1, 3, 2) (1, −1, 1) 110001011001 0b101010 (1, 3,2) (1, 1, −1) 110010100110 0b101011 (1, 3, 2) (1, −1, −1) 1100010101100b101100 (2, 1, 3) (1, 1, 1) 100111001010 0b101101 (2, 1, 3) (1, −1, 1)100100111010 0b101110 (2, 1, 3) (1, 1, −1) 100111000101 0b101111 (2, 1,3) (1, −1, −1) 100100110101 0b110000 (3, 2, 1) (1, 1, 1) 1010100111000b110001 (3, 2, 1) (1, −1, 1) 101001101100 0b110010 (3, 2, 1) (1, 1, −1)101010010011 0b110011 (3, 2, 1) (1, −1, −1) 101001100011 0b110100 (1,1, 1) (1, 1, 1) 110011001100 0b110101 (1, 1, 1) (1, −1, 1) 1100001111000b110110 (1, 1, 1) (1, 1, −1) 110011000011 0b110111 (1, 1, 1) (1, −1,−1) 110000110011 0b111000 (2, 2, 2) (1, 1, 1) 100110011001 0b111001 (2,2, 2) (1, −1, 1) 100101101001 0b111010 (2, 2, 2) (1, 1, −1) 1001100101100b111011 (2, 2, 2) (1, −1, −1) 100101100110 0b111100 (3, 3, 3) (1, 1, 1)101010101010 0b111101 (3, 3, 3) (1, −1, 1) 101001011010 0b111110 (3, 3,3) (1, 1, −1) 101010100101 0b111111 (3, 3, 3) (1, −1, −1) 101001010101

In quasi-orthogonal signal streams shown in Table 1 above, a mappingrelation between a codeword and a quasi-orthogonal signal stream maychange depending on an environment. More particularly, in a case where aquasi-orthogonal signal stream capable of representing up to 6-bitinformation intends to minimize a correlation value betweenquasi-orthogonal signal streams with respect to 4-bit or 5-bitinformation, an order of Reed-Solomon mapping of Equation (4) above ismodified as illustrated in Equation (7) below.

$\begin{matrix}\begin{bmatrix}\left( {v_{0},v_{0},v_{0}} \right) & \left( {v_{1},v_{1},v_{1}} \right) & \left( {v_{2},v_{2},v_{2}} \right) & \left( {v_{3},v_{3},v_{3}} \right) \\\left( {v_{0},v_{1},v_{2}} \right) & \left( {v_{1},v_{0},v_{3}} \right) & \left( {v_{2},v_{3},v_{0}} \right) & \left( {v_{3},v_{2},v_{1}} \right) \\\left( {v_{1},v_{3},v_{2}} \right) & \left( {v_{3},v_{1},v_{0}} \right) & \left( {v_{0},v_{2},v_{3}} \right) & \left( {v_{0},v_{3},v_{1}} \right) \\\left( {v_{1},v_{2},v_{0}} \right) & \left( {v_{2},v_{0},v_{1}} \right) & \left( {v_{2},v_{1},v_{3}} \right) & \left( {v_{3},v_{0},v_{2}} \right)\end{bmatrix} & (7)\end{matrix}$

In Equation (7), v_(k) denotes a (k+1)^(th) orthogonal sub-signalstream.

When quasi-orthogonal signal streams are configured by Equation (7)above, the quasi-orthogonal signal streams are expressed by Table 2below.

TABLE 2 signal stream codeword (BPSK) 0b000000 111111111111 0b000001111100001111 0b000010 111111110000 0b000011 111100000000 0b000100101010101010 0b000101 101001011010 0b000110 101010100101 0b000111101001010101 0b001000 110011001100 0b001001 110000111100 0b001010110011000011 0b001011 110000110011 0b001100 100110011001 0b001101100101101001 0b001110 100110010110 0b001111 100101100110 0b010000111110101100 0b010001 111101011100 0b010010 111110100011 0b010011111101010011 0b010100 101011111001 0b010101 101000001001 0b010110101011110110 0b010111 101000000110 0b011000 110010011111 0b011001110001101111 0b011010 110010010000 0b011011 110001100000 0b011100100111001010 0b011101 100100111010 0b011110 100111000101 0b011111100100110101 0b100000 101010011100 0b100001 101001101100 0b100010101010010011 0b100011 101001100011 0b100100 100110101111 0b100101100101011111 0b100110 100110100000 0b100111 100101010000 0b101000111111001001 0b101001 111100111001 0b101010 111111000110 0b101011111100110110 0b101100 111110011010 0b101101 111101101010 0b101110111110010101 0b101111 111101100101 0b110000 101011001111 0b110001101000111111 0b110010 101011000000 0b110011 101000110000 0b110100110011111010 0b110101 110000001010 0b110110 110011110101 0b110111110000000101 0b111000 110010101001 0b111001 110001011001 0b111010110010100110 0b111011 110001010110 0b111100 100111111100 0b111101100100001100 0b111110 100111110011 0b111111 100100000011

If 4-bit information is intended to be transmitted using thequasi-orthogonal signal streams shown in Table 2 above, a Mobile Station(MS) uses only 16 quasi-orthogonal signal streams, i.e., 0b000000 to0b001111, among 64 quasi-orthogonal signal streams in total. On theother hand, if 5-bit information is intended to be transmitted, the MSuses only 32 quasi-orthogonal signal streams, i.e., 0b000000 to0b011111. In addition, a correlation property is maintained even if amapping relation between a quasi-orthogonal signal stream and a codewordwith respect to 16 signal stream groups of {0b000000 to 0b001111} and{0b010000 to 0b011111} and the remaining 32 signal stream groups isarbitrarily modified within each signal stream group.

The mapping relation between the codeword and the signal stream of Table1 above is modified to a mapping relation as shown in Table 2 above inorder to transmit 4-bit and 5-bit information. In Table 2, the samegeneration process as for all signal stream groups is used.

Even if the mapping relation of codewords and signal streams shown inTable 1 and Table 2 above is newly defined, a correlation relation and aproperty of a maximum correlation value are maintained. Defining a newmapping relation is to change a method of mapping a signal stream to atime-frequency resource. In this case, a property of the signal streamdoes not change, but reception performance may vary in an environmentwhere a given time-frequency resource cannot have the same channel gaindue to high-speed movement, time and frequency errors, and the like.Table 3 below shows a signal stream obtained by rearranging the signalstream of Table 2 to have a more robust property in a fast movementenvironment.

TABLE 3 signal stream codeword (BPSK) 0b000000 111111111111 0b000001101111010110 0b000010 011010111101 0b000011 001010010100 0b000100110011001100 0b000101 100011100101 0b000110 010110001110 0b000111000110100111 0b001000 100110011001 0b001001 110110110000 0b001010000011011011 0b001011 010011110010 0b001100 101010101010 0b001101111010000011 0b001110 001111101000 0b001111 011111000001 0b010000111110011100 0b010001 101110110101 0b010010 011011011110 0b010011001011110111 0b010100 110010101111 0b010101 100010000110 0b010110010111101101 0b010111 000111000100 0b011000 100111111010 0b011001110111010011 0b011010 000010111000 0b011011 010010010001 0b011100101011001001 0b011101 111011100000 0b011110 001110001011 0b011111011110100010 0b100000 100110101100 0b100001 110110000101 0b100010000011101110 0b100011 010011000111 0b100100 111111001010 0b100101101111100011 0b100110 011010001000 0b100111 001010100001 0b101000101010011111 0b101001 111010110110 0b101010 001111011101 0b101011011111110100 0b101100 101011111100 0b101101 111011010101 0b101110001110111110 0b101111 011110010111 0b110000 100111001111 0b110001110111100110 0b110010 000010001101 0b110011 010010100100 0b110100110011111001 0b110101 100011010000 0b110110 010110111011 0b110111000110010010 0b111000 110010011010 0b111001 100010110011 0b111010010111011000 0b111011 000111110001 0b111100 111110101001 0b111101101110000000 0b111110 011011101011 0b111111 001011000010

Hereinafter, structures of a transmitting end and a receiving end whichuse a quasi-orthogonal signal stream group generated as described abovewill be described with reference to the accompanying drawings.

FIG. 3 is a block diagram illustrating a structure of a transmitting endin a broadband wireless communication system according to an exemplaryembodiment of the present invention.

Referring to FIG. 3, the transmitting end includes a feedback encoder302, a signal stream generator 304, a plurality of bundle mappers 306-1to 306-3, an OFDM modulator 308 and a Radio Frequency (RF) transmitter310.

The feedback encoder 302 converts information to be fed back through afast feedback channel into a codeword. That is, the feedback encoder 302converts the information to be fed back into the codeword according to apredefined rule.

The signal stream generator 304 receives the codeword from the feedbackencoder 302 and generates a quasi-orthogonal signal stream correspondingto the codeword. In this case, the quasi-orthogonal signal stream isdetermined by a predefined mapping relation between a codeword and thequasi-orthogonal signal stream. In addition, the quasi-orthogonal signalstream has a format that differs depending on a design rule of thequasi-orthogonal signal stream. Herein, the design rule includes athreshold of a correlation value between different quasi-orthogonalsignal streams, the number of codewords to be used, and the like. Forexample, the format of the quasi-orthogonal signal stream and themapping relation between the codeword and the quasi-orthogonal signalstream are shown in Table 2 and Table 3 above. That is, signal streamgenerator 304 stores a predefined quasi-orthogonal signal stream groupand information on the mapping relation between the codeword and thequasi-orthogonal signal stream, evaluates a quasi-orthogonal signalstream corresponding to a codeword provided from the feedback encoder302, and generates the quasi-orthogonal signal stream consisting ofcomplex symbols.

The bundle mappers 306-1 to 306-3 map the quasi-orthogonal signal streamprovided from the signal stream generator 304 to each bundle in the fastfeedback channel. In this case, the bundle mappers 306-1 to 306-3 mapthe quasi-orthogonal signal stream so that one orthogonal sub-signalstream is located in physically contiguous tones. Further, the bundlemappers 306-1 to 306-3 map the quasi-orthogonal signal stream so thatorthogonal sub-signal streams are arranged in different orders in eachbundle. That is, each of the bundle mappers 306-1 to 306-3 arrangesorthogonal sub-signal streams constituting the quasi-orthogonal signalstream in different orders while mapping the same quasi-orthogonalsignal stream to a corresponding bundle. For example, when using thesignal stream of Table 3 above, the bundle mappers 306-1 to 306-3 mapquasi-orthogonal signal streams as illustrated in FIG. 2A above. Such amapping method is the same as a method of mapping quasi-orthogonalsignal streams as illustrated in FIG. 2B above by using the signalstream of Table 2 above.

The OFDM modulator 308 converts signals mapped by the bundle mappers306-1 to 306-3 into time-domain signals by performing an Inverse FastFourier Transform (IFFT) operation, and configures OFDM symbols byinserting a Cyclic Prefix (CP). The RF transmitter 310 up-converts theOFDM symbols provided from the OFDM modulator 308 into an RF signal andthen transmits the RF signal through an antenna.

FIG. 4 is a block diagram illustrating a structure of a receiving end ina broadband wireless communication system according to an exemplaryembodiment of the present invention.

Referring to FIG. 4, the receiving end includes an RF receiver 402, anOFDM demodulator 404, a plurality of bundle extractors 406-1 to 406-3, aplurality of signal stream sorters 408-1 to 408-3, a plurality of signalstream correlation units 410-1 to 410-3, a plurality of squarers 412-1to 412-3, a codeword determination unit 414 and a feedback decoder 416.

The RF receiver 402 converts an RF signal received through an antennainto a baseband signal. The OFDM demodulator 404 divides a signalprovided from the RF receiver 402 in an OFDM symbol unit, removes a CPand then restores complex symbols mapped to a frequency domain byperforming a Fast Fourier Transform (FFT) operation.

The bundle extractors 406-1 to 406-3 extract complex symbols mapped to afast feedback channel. In this case, each of the bundle extractors 406-1to 406-3 extracts complex symbols mapped to a bundle managed by eachbundle extractor. For example, if the fast feedback channel has a formatas illustrated in FIG. 1, the bundle extractor 406-1 extracts complexsymbols mapped to a first bundle 111, the bundle extractor 406-2extracts complex symbols mapped to a second bundle 113, and the bundleextractor 406-3 extracts complex symbols mapped to a third bundle 115,Although complex symbols mapped to each bundle are elements of the samequasi-orthogonal signal stream, the elements of the quasi-orthogonalsignal stream may be arranged differently depending on a bundle.

The signal stream sorters 408-1 to 408-3 sort complex symbols providedfor each bundle from the bundle extractors 406-1 to 406-3. In otherwords, the signal stream sorters 408-1 to 408-3 sort complex symbolsextracted from each bundle in a format used before mapping and thusconfigure unmapped quasi-orthogonal signal streams. The quasi-orthogonalsignal stream is decomposed in an orthogonal sub-signal stream unit by atransmitting end, and then is mapped to a predefined pattern thatdiffers depending on a bundle. Therefore, each of the signal streamsorters 408-1 to 408-3 sorts complex symbols according to a mappingpattern of a bundle managed by each signal stream sorter. For example,the mapping pattern of each bundle is illustrated in FIG. 2A or FIG. 2B.

The signal stream correlation units 410-1 to 410-3 determine correlationvalues between candidate quasi-orthogonal signal streams and aquasi-orthogonal signal stream received according to each bundle.Herein, the candidate quasi-orthogonal signal streams include allavailable quasi-orthogonal signal streams. That is, the signal streamcorrelation units 410-1 to 410-3 store a list of the candidatequasi-orthogonal signal streams. Upon receiving the quasi-orthogonalsignal stream, each of the signal stream correlation units 410-1 to410-3 performs a correlation operation between each of the candidatequasi-orthogonal signal streams and the quasi-orthogonal signal streamreceived according to a bundle managed by each signal stream correlationunit. For example, the correlation operation is performed as illustratedin Equation (2) above. Therefore, each of the signal stream correlationunits 410-1 to 410-3 outputs correlation values as many as the number ofcandidate quasi-orthogonal signal streams. The squarers 412-1 to 412-3determine square values of the correlation values provided from thesignal stream correlation units 410-1 to 410-3.

By using the square values provided from the squarers 412-1 to 412-3,the codeword determination unit 414 determines a quasi-orthogonal signalstream transmitted by the transmitting end. For this, the codeworddetermination unit 414 sums square correlation values derived from thesame candidate quasi-orthogonal signal stream. Accordingly, the numberof the determined square correlation values is equal to the number ofcandidate quasi-orthogonal signal streams. Thereafter, the codeworddetermination unit 414 searches for a maximum value among the sums ofthe square correlation values and determines that a quasi-orthogonalsignal stream corresponding to the maximum value is transmitted. Thecodeword determination unit 414 outputs a codeword corresponding to thequasi-orthogonal signal stream corresponding to the maximum value. Thefeedback decoder 416 analyzes the codeword to evaluate controlinformation expressed by the codeword.

FIG. 5A is a block diagram illustrating a structure of a receiving endin a broadband wireless communication system according to an exemplaryembodiment of the present invention.

Referring to FIG. 5A, the receiving end includes an RF receiver 510, anOFDM demodulator 520, a plurality of bundle extractors 530-1 to 530-3, aplurality of signal stream sorters 540-1 to 540-3, a plurality ofsub-signal stream correlation units 550-1-1 to 550-3-K, an indexdetector 560, a phase difference detector 570, a codeword determinationunit 580 and a feedback decoder 590.

The RF receiver 510 converts an RF signal received through an antennainto a baseband signal. The OFDM demodulator 520 divides a signalprovided from the RF receiver 510 in an OFDM symbol unit, removes a CPand then restores complex symbols mapped to a frequency domain byperforming an FFT operation.

The bundle extractors 530-1 to 530-3 extract complex symbols mapped to afast feedback channel. In this case, each of the bundle extractors 530-1to 530-3 extracts complex symbols mapped to a bundle managed by eachbundle extractor. For example, if the fast feedback channel has a formatas illustrated in FIG. 1, the bundle extractor 530-1 extracts complexsymbols mapped to a first bundle 111, the bundle extractor 530-2extracts complex symbols mapped to a second bundle 113 and the bundleextractor 530-3 extracts complex symbols mapped to a third bundle 115.Although complex symbols mapped to each bundle are elements of the samequasi-orthogonal signal stream, the elements of the quasi-orthogonalsignal stream may be arranged differently depending on a bundle.

Each of the signal stream sorters 540-1 to 540-3 sorts complex symbolsrespectively provided from the bundle extractors 530-1 to 530-3. Inother words, the signal stream sorters 540-1 to 540-3 sort complexsymbols extracted from each bundle in a format used before mapping andthus configure unmapped quasi-orthogonal signal streams. Thequasi-orthogonal signal stream is decomposed in an orthogonal sub-signalstream unit by a transmitting end and is mapped to a predefined patternthat differs depending on a bundle. Therefore, each of the signal streamsorters 540-1 to 540-3 sorts complex symbols according to a mappingpattern of a bundle managed by each signal stream sorter. Further, eachof the signal stream sorters 540-1 to 540-3 decomposes thequasi-orthogonal signal stream into orthogonal sub-signal streams andthen provides the sub-signal stream correlation units 550-1-1 to 550-3-Kwith the orthogonal sub-signal streams in a divisive manner.

The sub-signal stream correlation units 550-1-1 to 550-3-K determinecorrelation values between candidate orthogonal sub-signal streams andthe orthogonal sub-signal streams provided from the signal sorter 540-1to 540-3. That is, the sub-signal stream correlation units 550-1-1 to550-3-K store a list of the candidate orthogonal sub-signal streams.Upon receiving the orthogonal sub-signal stream, each of the sub-signalstream correlation units 550-1-1 to 550-3-K performs a correlationoperation between each of the candidate orthogonal sub-signal streamsand the received orthogonal sub-signal stream. For example, thecorrelation operation is performed as illustrated in Equation (2) above.Therefore, each of the signal stream correlation sub-signal streamcorrelation units 550-1-1 to 550-3-K outputs correlation values as manyas the number of candidate orthogonal sub-signal streams. That is, thenumber of the determined correlation values is equal to the productbetween the number of candidate orthogonal sub-signal stream per bundleand the number of orthogonal sub-signal stream constituting onequasi-orthogonal signal streams.

The index detector 560 detects an orthogonal sub-signal stream indexcombination of the transmitted quasi-orthogonal signal stream by usingcorrelation values provided from the sub-signal stream correlation units550-1-1 to 550-3-K. A detailed structure and function of the indexdetector 560 will be described below with reference to FIG. 5B. Thephase difference detector 570 detects a phase difference vector appliedto the transmitted quasi-orthogonal signal stream by using correlationvalues provided from the sub-signal stream correlation units 550-1-1 to550-3-K. A detailed structure and function of the phase differencedetector 570 will be described below with reference to FIG. 5C.

The codeword determination unit 580 determines a quasi-orthogonal signalstream transmitted by the transmitting end by using the phase differencevector and the index combination detected by the index detector 560 andthe phase difference detector 570. In other words, the codeworddetermination unit 580 determines that transmission is performed byapplying the detected phase difference vector to a quasi-orthogonalsignal stream consisting of orthogonal sub-signal streams correspondingto the detected index combination. The codeword determination unit 580outputs a codeword corresponding to the quasi-orthogonal signal stream.The feedback decoder 590 analyzes the codeword to evaluate controlinformation expressed by the codeword.

FIG. 5B is a block diagram illustrating a structure of an index detectorin a broadband wireless communication system according to an exemplaryembodiment of the present invention.

Referring to FIG. 5B, the index detector 560 includes a plurality ofsquarers 562-1-1 to 562-3-K, a plurality of adders 564-1 to 564-K and amaximum value search unit 566.

The squarers 562-1-1 to 562-3-K determine square values of thecorrelation values of orthogonal sub-signal streams provided from thesub-signal stream correlation units 550-1-1 to 550-3-K. In this case,each of the squarers 562-1-1 to 562-3-K receives correlation values asmany as the number of candidate sub-signal streams and determines squarecorrelation values as many as the number of candidate sub-signalstreams. As a result, the number of the determined square correlationvalues per bundle is equal to the product between the number ofcandidate orthogonal sub-signal stream and the number of orthogonalsub-signal stream constituting one quasi-orthogonal signal stream.

For each orthogonal sub-signal stream, the adders 564-1 to 564-K sum thesquare correlation values provided from the squarers 562-1-1 to 562-3-K.In other words, the adders 564-1 to 564-K sum the determined squarecorrelation values derived from the same candidate orthogonal sub-signalstream. In this case, each of the adders 564-1 to 564-K receives onlysquare correlation values for an orthogonal sub-signal stream located ina position managed by each adder. That is, the addition operation isperformed on the square correlation values derived from the samecandidate orthogonal sub-signal stream among square correlation valuesof orthogonal sub-signal stream located in the same position. Forexample, the adder 564-1 manages a first position and receives squarecorrelation values as many as the number of candidate orthogonalsub-signal streams respectively from the squarers 562-1-1, 562-2-1 and562-3-1. Further, the adder 564-1 sums square correlation values derivedfrom the same candidate orthogonal sub-signal stream among squarecorrelation values as many as the number of candidate orthogonalsub-signal streams provided respectively from the squarers 562-1-1,562-2-1 and 562-3-1, and outputs sums of the square correlation valuesas many as the number of orthogonal sub-signal streams. Accordingly, thenumber of the determined sums of the square correlation values is thesame as the number of candidate orthogonal sub-signal streams for eachposition of the orthogonal sub-signal stream.

The maximum value search unit 566 searches for a maximum value for eachposition of an orthogonal sub-carrier among the sums of the squarecorrelation values. In other words, the maximum value search unit 566searches for a maximum value corresponding to each of the adders 564-1to 564-K among the sums of the square correlation values providedrespectively from the adders 564-1 to 564-K. That is, the maximum valuesearch unit 566 searches for maximum values as many as the number oforthogonal sub-signal streams constituting one quasi-orthogonal signalstream. As a result, the maximum values corresponding to positions ofthe respective orthogonal sub-signal streams are searched for. Further,the maximum value search unit 566 evaluates indices of orthogonalsub-signal streams corresponding to the maximum values, and provides thecodeword determination unit 580 with an index combination in which theevaluated indices are listed.

FIG. 5C is a block diagram illustrating a structure of a phasedifference detector in a broadband wireless communication systemaccording to an exemplary embodiment of the present invention.

Referring to FIG. 5C, the phase difference detector 570 includes aplurality of phase difference vector multipliers 572-1 to 572-3, aplurality of squarers 574-1 to 574-3, an adder 576 and a maximum valuesearch unit 578.

The phase difference vector multipliers 572-1 to 572-3 multiplycorrelation values of orthogonal sub-signal streams provided from thesub-signal stream correlation units 550-1-1 to 550-3-K by a phasedifference vector. In this case, the phase difference vector multipliers572-1 to 572-3 sequentially use available phase difference vectors.Further, the phase difference vector multipliers 572-1 to 572-3 multiplycorrelation values by elements of a phase difference vectorcorresponding to a position of a specific orthogonal sub-signal stream.For example, the phase difference vector multiplier 572-1 sequentiallymultiplies the correlation value provided from the sub-signalcorrelation unit 550-1-1 by each of first elements of the phasedifference vectors. Further, the phase difference vector multipliers572-1 to 572-3 sum the correlation values multiplied by each element ofthe phase difference vectors. In this case, a summation operation isperformed on correlation values of an orthogonal sub-signal streamincluded in the same bundle. As a result, the number of the sums of thecorrelation values is equal to the number of phase difference vectorsper bundle.

The squarers 574-1 to 574-3 determine square values of the sums of thecorrelation values multiplied by the phase difference vectors providedfrom the phase difference vector multipliers 572-1 to 572-3. In thiscase, the sums of the correlation values are sequentially provided asmany as the number of available phase difference vectors respectivelyfrom the phase difference vector multipliers 572-1 to 572-3.Accordingly, each of the squarers 574-1 to 574-3 sequentially outputssquare values of the sums of the correlation values as many as thenumber of available phase difference vectors.

The adder 576 receives the square values of the sums of the correlationvalues from the squarers 574-1 to 574-3 and then sums the receivedsquare values. In this case, the square values of the sums of thecorrelation values are sequentially provided as many as the number ofavailable phase difference vectors and the adder 576 outputs the sums ofthe square values as many as the number of available phase differencevectors. Accordingly, the number of the determined sums of the squarevalues is equal to the number of available phase difference vectors. Inthis case, the sums of the square values respectively correspond to thephase difference vectors.

The maximum value search unit 578 searches for a maximum value among thesums of the square values sequentially provided. Further, the maximumvalue search unit 578 evaluates a phase difference vector correspondingto the maximum value and reports the evaluated phase difference vectorto the codeword determination unit 580.

Hereinafter, operations of a transmitting end and a receiving end whichuse a quasi-orthogonal signal stream group generated as described abovewill be described with reference to the accompanying drawings.

FIG. 6 is a flowchart illustrating a process of transmitting aquasi-orthogonal signal stream of a transmitting end in a broadbandwireless communication system according to an exemplary embodiment ofthe present invention.

Referring to FIG. 6, the transmitting end generates a quasi-orthogonalsignal stream to be transmitted through a fast feedback channel in step601. In this case, the quasi-orthogonal signal stream is determined by amapping relation between a predefined codeword and the quasi-orthogonalsignal stream. In addition, the quasi-orthogonal signal has a formatthat differs depending on a design rule of the quasi-orthogonal signalstream. Herein, the design rule includes a threshold of a correlationvalue between different quasi-orthogonal signal streams, the number ofcodewords to be used, and the like. For example, the format of thequasi-orthogonal signal stream and the mapping relation between thecodeword and the quasi-orthogonal signal stream are shown in Table 2 andTable 3 above.

After the quasi-orthogonal signal stream is generated, the transmittingend maps the quasi-orthogonal signal stream to three bundles indifferent patterns in step 603. That is, the transmitting end maps thequasi-orthogonal signal stream so that one orthogonal sub-signal streamis located in physically contiguous tones. Further, the transmitting endmaps the quasi-orthogonal signal stream so that orthogonal sub-signalstreams are arranged in different orders in each bundle. In other words,the transmitting end arranges orthogonal sub-signal streams constitutingthe quasi-orthogonal signal stream in different orders while mapping thesame quasi-orthogonal signal stream to bundles. For example, thetransmitting end maps the quasi-orthogonal signal stream as illustratedin FIG. 2A or FIG. 2B above.

After mapping the quasi-orthogonal signal stream, the transmitting endtransmits the quasi-orthogonal signal stream mapped to the fast feedbackchannel in step 605. That is, the transmitting end configures OFDMsymbols by performing an IFFT operation and CP insertion, up-convertsthe OFDM symbols into an RF signal and then transmits the RF signalthrough an antenna.

FIG. 7 is a flowchart illustrating a process of detecting aquasi-orthogonal signal stream of a receiving end in a broadbandwireless communication system according to an exemplary embodiment ofthe present invention.

Referring to FIG. 7, the receiving end extracts complex symbols receivedthrough a fast feedback channel in step 701. That is, the receiving enddown-converts an RF signal received through an antenna into a basebandsignal, restores complex symbols mapped to a frequency domain byperforming CP removal and an FFT operation, and then extracts complexsymbols mapped to the fast feedback channel. In this case, the receivingend divides the complex symbols according to a bundle. Although complexsymbols mapped to each bundle are elements of the same quasi-orthogonalsignal stream, the elements of the quasi-orthogonal signal stream may bearranged differently depending on a bundle.

After extracting the complex symbols, the receiving end configuresquasi-orthogonal signal streams per bundle by sorting complex symbolsper bundle in step 703. The quasi-orthogonal signal stream is decomposedin an orthogonal sub-signal stream unit by a transmitting end and ismapped to a predefined pattern that differs depending on a bundle.Therefore, the receiving end sorts complex symbols according to amapping pattern of each bundle. For example, the mapping pattern of eachbundle is illustrated in FIG. 2A or FIG. 2B.

After configuring the quasi-orthogonal signal streams per bundle, thereceiving end determines correlation values between receivedquasi-orthogonal signal streams and candidate quasi-orthogonal signalstreams in step 705. In other words, the receiving end performs acorrelation operation between each of the candidate quasi-orthogonalsignal streams and the quasi-orthogonal signal stream received accordingto each bundle. For example, the correlation operation is performed asillustrated in Equation (2) above. Therefore, the number of determinedcorrelation values is equal to the number of candidate quasi-orthogonalsignal streams. The receiving end determines square values of thecorrelation values.

After determining the square values of the correlation values, thereceiving end determines a transmitted quasi-orthogonal signal stream byusing the square values of the correlation values in step 707. That is,the receiving end adds the square correlation values for eachquasi-orthogonal signal stream used to determine correlation values.Accordingly, the number of the determined square correlation values isequal to the number of candidate quasi-orthogonal signal streams.Thereafter, the receiving end searches for a maximum value among thesums of the square correlation values and determines that aquasi-orthogonal signal stream corresponding to the maximum value istransmitted.

FIG. 8A is a flowchart illustrating a process of detecting aquasi-orthogonal signal stream of a receiving end in a broadbandwireless communication system according to an exemplary embodiment ofthe present invention.

Referring to FIG. 8B, the receiving end extracts complex symbolsreceived through a fast feedback channel in step 801. That is, thereceiving end down-converts an RF signal received through an antennainto a baseband signal, restores complex symbols mapped to a frequencydomain by performing CP removal and an FFT operation and then extractscomplex symbols mapped to the fast feedback channel. In this case, thereceiving end divides the complex symbols according to a bundle.Although complex symbols mapped to each bundle are elements of the samequasi-orthogonal signal stream, the elements of the quasi-orthogonalsignal stream may be arranged differently depending on a bundle.

After extracting the complex symbols, the receiving end configuresquasi-orthogonal signal streams per bundle by sorting complex symbolsper bundle in step 803. The quasi-orthogonal signal stream is decomposedin an orthogonal sub-signal stream unit by a transmitting end and ismapped to a predefined pattern that differs depending on a bundle.Therefore, the receiving end sorts complex symbols according to amapping pattern of each bundle. For example, the mapping pattern of eachbundle is illustrated in FIG. 2A or FIG. 2B.

After configuring the quasi-orthogonal signal streams per bundle, thereceiving end determines correlation values between received orthogonalsub-signal stream and candidate orthogonal sub-signal streams in step805. In other words, the receiving end performs a correlation operationbetween each of the candidate orthogonal sub-signal streams and theorthogonal sub-signal stream received according to each bundle. Forexample, the correlation operation is performed as illustrated inEquation (2) above. Therefore, the number of determined correlationvalues is equal to the product between the number of candidateorthogonal sub-signal streams per bundle and the number of orthogonalsub-signal streams constituting one quasi-orthogonal signal stream.

After determining the correlation values, the receiving end detects asub-signal stream index and a phase difference vector by using thecorrelation values in step 807. In other words, the receiving endevaluates an index of orthogonal sub-signal streams constituting atransmitted quasi-orthogonal sub-signal streams and also evaluates anapplied phase difference vector. A detailed process for detecting thesub-signal stream index and a detailed process for detecting the phasedifference vector will be described with reference to FIG. 8B and FIG.8C.

After detecting the sub-signal stream index and the phase differencevector, the receiving end determines a transmitted quasi-orthogonalsignal stream by using the sub-signal stream index and the phasedifference vector in step 809. In other words, the receiving enddetermines that transmission is performed by applying the detected phasedifference vector to a quasi-orthogonal signal stream consisting oforthogonal sub-signal streams corresponding to a combination of thedetected index combination.

FIG. 8B is a flowchart illustrating a process of detecting a sub-signalstream index of a receiving end in a broadband wireless communicationsystem according to an exemplary embodiment of the present invention.

Referring to FIG. 8B, the receiving end determines square values ofcorrelation values between received orthogonal sub-signal streams andcandidate orthogonal sub-signal streams in step 811. Therefore, thenumber of determined correlation values is equal to the product betweenthe number of candidate orthogonal sub-signal stream per bundle and thenumber of orthogonal sub-signal stream constituting one quasi-orthogonalsignal stream.

After determining the square correlation values, the receiving end sumsthe square correlation values for each received orthogonal sub-signalstream in step 813. In other words, the receiving end adds squarecorrelation values of the same orthogonal sub-signal stream. In thiscase, the addition operation is performed on the square correlationvalues derived from the same candidate orthogonal sub-signal streamamong square correlation values of orthogonal sub-signal stream locatedin the same position, and the added square correlation values arepresent as many as the number of bundles. Accordingly, the number of thedetermined sums of the square correlation values is equal to the numberof candidate orthogonal sub-signal streams for each position of anorthogonal sub-signal stream.

After adding the square correlation values for each orthogonalsub-signal stream, the receiving end searches for a maximum value foreach position of an orthogonal sub-signal stream among the squarecorrelation values in step 815. That is, the receiving end searches formaximum values as many as the number of orthogonal sub-signal streamsconstituting one quasi-orthogonal signal stream. As a result, themaximum values corresponding to positions of the respective orthogonalsub-signal streams are searched for.

After searching for the maximum value for each position of theorthogonal sub-signal stream, the receiving end evaluates an index of anorthogonal sub-signal stream corresponding to each of the maximum valuein step 817. In other words, the receiving end evaluates an orthogonalsub-signal stream index corresponding to a position of each orthogonalsub-signal stream. As a result, indices of orthogonal sub-signal streamsconstituting the quasi-orthogonal signal stream are evaluated.

FIG. 8C is a flowchart illustrating a process of detecting a phasedifference vector of a receiving end in a broadband wirelesscommunication system according to an exemplary embodiment of the presentinvention.

Referring to FIG. 8C, the receiving end performs multiplication andaddition on correlation values and phase difference vectors in step 821.In this case, the receiving end sequentially uses available phasedifference vectors. In addition, the receiving end multiplies acorrelation value by an element of a phase difference vectorcorresponding to a position of a specific orthogonal sub-signal stream.That is, correlation values of an orthogonal sub-signal stream in afirst position are multiplied by a first element of the phase differencevector. In this case, the addition operation is performed on correlationvalues of an orthogonal sub-signal stream included in the same bundle.As a result, the number of the determined sums of the correlation valuesis equal to the number of phase difference vectors per bundle.

After performing multiplication and addition on the phase differencevectors, the receiving end determines square values of sums ofcorrelation values in step 823. In this case, sums of correlation valuesare present as many as the number of available phase difference vectorsper bundle. Accordingly, the number of the determined square values ofsums of correlation values is equal to the number of available phasedifference vectors.

After determining the square values of the sums of the correlationvalues, the receiving end sums square values corresponding to the samephase difference vector in step 825. In this case, square values of sumsof correlation values are present as many as the number of availablephase difference vectors per bundle. Therefore, the number of thedetermined sums of the square values is equal to the number of availablephase difference vectors. The sums of the square values respectivelycorrespond to phase difference vectors.

After summing the square values, the receiving end evaluates a phasedifference vector corresponding to a maximum value among the sums of thesquare values in step 827. That is, the receiving end searches formaximum values among the sums of the square values and evaluates a phasedifference vector corresponding to the maximum value.

According to exemplary embodiments of the present invention, a broadbandwireless communication system uses a quasi-orthogonal signal stream toincrease an amount of information transmitted and received through afast feedback channel. In addition, despite the increased informationamount, accurate information delivery and reliable system operation arepossible without being affected by a channel estimation error or thelike.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A transmitting-end apparatus in a wirelesscommunication system, the apparatus comprising: a plurality of mappersfor mapping a sequence, corresponding to an index to be fed back, to afirst set of resource blocks in a fast feedback channel by using a firstmapping pattern and to a second set of resource blocks in the fastfeedback channel by using a second mapping pattern; and a transmitterfor transmitting the sequence mapped to a plurality of sets of resourceblocks, wherein the sequence is mapped to each of the plurality of setsof resource blocks, and wherein each element of the sequence is mappedto each resource block, wherein a mapping order of elements of thesequence in the first mapping pattern is different from a mapping orderof elements of the sequence in the second mapping pattern, wherein thefirst set of resource blocks and second set of resource blocks have apredetermined same number of resource blocks each other, and wherein thefirst set of resource blocks is differently located from the second setof resource block in the fast feedback channel.
 2. The apparatus ofclaim 1, wherein the sequence comprises one of sequences included in asequence group designed such that a correlation value between allpossible signal pairs is one of less than and equal to a threshold. 3.The apparatus of claim 1, wherein the sequence is determined as one ofpredefined candidates, the predefined candidates comprising‘111111111111’, ‘101111010110’, ‘011010111101’, ‘001010010100’,‘101010101010’, ‘111010000011’, ‘001111101000’, ‘011111000001’,‘110011001100’, ‘100011100101’, ‘010110001110’, ‘000110100111’,‘100110011001’, ‘110110110000’, ‘000011011011’, ‘010011110010’,101011111100’, ‘111011010101’, ‘001110111110’, ‘011110010111’,‘111110101001’, ‘101110000000’, ‘011011101011’, ‘001011000010’,‘100111001111’, ‘110111100110’, ‘000010001101’, ‘010010100100’,‘110010011010’, ‘100010110011’, ‘010111011000’, ‘000111110001’,101011001001′, ‘111011100000’, ‘001110001011’, ‘011110100010’,‘100111111010’, ‘110111010011’, ‘000010111000’, ‘010010010001’,‘111110011100’, ‘101110110101’, ‘011011011110’, ‘001011110111’,‘101010011111’, ‘111010110110’, ‘001111011101’, ‘011111110100’,111111001010′, ‘101111100011’, ‘011010001000’, ‘001010100001’,‘110010101111’, ‘100010000110’, ‘010111101101’, ‘000111000100’,‘100110101100’, ‘110110000101’, ‘000011101110’, ‘010011000111’,‘110011111001’, ‘100011010000’, ‘010110111011’ and ‘000110010010’. 4.The apparatus of claim 3, wherein the mappers map the sequence to threesets of resource blocks comprising a size of 6×2 in a time axis and asymbol axis, wherein, for the first set of resource blocks, the mappersmap a 0th element, a 2nd element, a 4th element, a 6th element, a 8thelement and a 10th element, in that order, in first row of a frequencyaxis, and maps the 1st element, the 3rd element, the 5th element, the7th element, the 9th element, and the 11th element, in that order, insecond row of the frequency axis, wherein, for the second set ofresource blocks, the mappers map the 9th element, the 11th element, the4th element, the 0th element, the 2nd element and the 7th element, inthat order, in first row of the frequency axis, and maps the 10thelement, the 3rd element, the 5th element, the 1st element, the 6thelement and the 8th element, in that order, in second row of thefrequency axis, and wherein, for a third set of resource blocks, themappers map the 3rd element, the 5th element, the 7th element, the 9thelement, the 11th element and the 1st element, in that order, in firstrow of the frequency axis, and maps the 4th element, the 6th ellement,the 8th element, the 10th element, the 0th element and the 2nd element,in that order, in second row of the frequency axis.
 5. A method fortransmitting feedback information through a fast feedback channel in awireless communication system, the method comprising: mapping asequence, corresponding to an index to be fed back, to a first set ofresource blocks in a fast feedback channel by using a first mappingpattern and to a second set of resource blocks in the fast feedbackchannel by using a second mapping pattern; and transmitting the sequencemapped to a plurality of sets of resource blocks, wherein the sequenceis mapped to each of the plurality of sets of resource blocks, andwherein each element of the sequence is mapped to each resource block,wherein a mapping order of elements of the sequence in the first mappingpattern is different from a mapping order of elements of the sequence inthe second mapping pattern, wherein the first set of resource blocks andsecond set of resource blocks have a predetermined same number ofresource blocks each other, and wherein the first set of resource blocksis differently located from the second set of resource block in the fastfeedback channel.
 6. The method of claim 5, wherein the sequencecomprises one of sequences included in a sequence group designed suchthat a correlation value between all possible signal pairs is one ofless than and equal to a threshold.
 7. The method of claim 5, whereinthe sequence is determined as one of predefined candidates, thepredefined candidates comprising ‘111111111111’, ‘101111010110’,‘011010111101’, ‘001010010100’, ‘101010101010’, ‘111010000011’,‘001111101000’, ‘011111000001’, ‘110011001100’, ‘100011100101’,‘010110001110’, ‘000110100111’, ‘100110011001’, ‘110110110000’,‘000011011011’, ‘010011110010’, ‘01011111100’, ‘111011010101’,‘001110111110’, ‘011110010111’, ‘111110101001’, ‘101110000000’,‘011011101011’, ‘001011000010’, ‘100111001111’, ‘110111100110’,‘000010001101’, ‘010010100100’, ‘110010011010’, ‘100010110011’,‘010111011000’, ‘000111110001’, 101011001001′, ‘111011100000’,‘001110001011’, ‘011110100010’, ‘100111111010’, ‘110111010011’,‘000010111000’, ‘010010010001’, ‘111110011100’, ‘101110110101’,‘011011011110’, ‘001011110111’, ‘101010011111’, ‘111010110110’,‘001111011101’, ‘011111110100’, 111111001010′, ‘101111100011’,‘011010001000’, ‘001010100001’, ‘110010101111’, ‘100010000110’,‘010111101101’, ‘000111000100’, ‘100110101100’, ‘110110000101’,‘000011101110’, ‘010011000111’, ‘110011111001’, ‘100011010000’,‘010110111011’ and ‘000110010010’.
 8. The method of claim 7, wherein thesequence is mapped to three sets of resource blocks comprising a size of6×2 in a time axis and a symbol axis, wherein, for the first set ofresource blocks, a 0th element, a 2nd element, a 4th element, a 6thelement, a 8th element and a 10th element are mapped, in that order, infirst row of a frequency axis, and symbols 1, 3, 5, 7, 9 and 11 aremapped, in that order, in second row of the frequency axis, wherein, forthe second set of resource blocks, the 9th element, the 11th element,the 4th element, the 0th element, the 2nd element and the 7th elementare mapped, in that order, in first row of the frequency axis, and the10th element, the 3rd element, the 5th element, the 1st element, the 6thelement and the 8th element are mapped, in that order, in second row ofthe frequency axis, and wherein, for a third set of resource blocks, the3rd element, the 5th element, the 7th element, the 9th element, the 11thelement and the 1st element are mapped, in that order, in first row ofthe frequency axis, and the 4th element, the 6th ellement, the 8thelement, the 10th element, the 0th element and the 2nd element aremapped, in that order, in second row of the frequency axis.